Liquid filters are used for a variety of applications, for example to filter lubricating fluids, fuels or hydraulic fluids. During use, liquid to be filtered is passed through a filter media, as filtration occurs. A well-known configuration, is to position the filter media as a cylinder surrounding a central clean liquid volume, with filtration flow occurring with an outside to inside (out-to-in) flow through the filter media. In other arrangements filtering flow is from inside the cartridge to outside (in-to-out).
In many instances, the filter media is provided in the form of filter cartridge, in extension between first and second, opposite, end caps. Typically, the arrangement is also provided with a liner. For an out-to-in flow, an inner liner provides for both: (a) radial support of the media against collapse or damage, due to radial pressure during normal use; and (b) axial support against cartridge collapse and damage. Examples of filter cartridges which utilize such constructions, are described for example in WO 02/070869 A1 published 12 Sep. 2002, (FIGS. 1 and 2), the complete disclosure of WO 02/070869 being incorporated herein by reference.
With an in-to-out flow, an outer liner can be used to provide media radial support and also axial support.
In many assemblies, the filter cartridge is constructed as a removable and replaceable (i.e., serviceable) component, see for example FIGS. 1 and 2 of WO 02/070869 A1. It is desirable to provide for liquid filter designs that allow for desired options in construction of service cartridges.